text:
How did planes measure their speed relative to the ground before GPS?
How did planes measure their ground speed before GPS?
If they used some sort of anemometer to measure speed, that would only measure the speed of the plane relative to the air through which it is passing.
Therefore, I'm wondering how speed relative to the ground was measured before GPS.
I'd be very grateful if someone could explain this to me!

Your "plane staying over the same point in the earth" happens all the time, except "plane" is a helicopter. I've even flown a 172 with a zero ground speed (hovering), which was possible with a strong headwind. Yes it will show zero because GPS measures ground speed, not air speed.

GPS satellites are on 12-hour orbits, much lower than geostationary. They always have very substantial speed with respect to the normal user. This is what makes initial fix difficult: the receiver needs to account for the Doppler shift in the frequency of each satellite, and if the constellation at this moment is not known exactly, the receiver needs to sweep through a range of frequencies rather than just tune to a 'station'. But for measurement it doesn't matter much: the system just applies some math to compensate for all these effects. It would have to anyway.

No, GPS satellites are not in geostationary orbit -- Removed from the question.

Major edit here: The question appeared more like a ramble, so I carefully picked through and clarified what is actually being asked here.  Many answers are responding to the asker's general confusion due to unfamiliarity with the subject matter rather than the specific question being asked.  The second question being asked: How does GPS measure a plane's ground speed?

100 feet between every telephone pole

I'm wondering if they had ground distance from a map, and their air speed, altitude, and total distance to cover so they had a close calculation of how fast they would be going "groundspeed" at a given altitude for the duration of the trip?

See https://en.wikipedia.org/wiki/1947_BSAA_Avro_Lancastrian_Star_Dust_accident for an unfortunate example of what could happen if you got your ground speed estimation wrong due to wind.

I've heard stories of a C-172 flying reverse due to extremely strong headwind during a slow flight maneuver.

The other answers seem to make a simple thing way too complicated. Yes there are DMEs or TACANs, that are sometimes used to get a ground speed, but it's only accurate if you're tracking exactly to or away from it. And it certainly wasn't used to calculate speed enroute unless one of your navaids was a VOR/DME or equivalent. Rather than using DME they'd be using INS, which delivers data more similar to GPS.
Calculating ground speed in the past (before INS, or in airplanes without one) was done using the simple method of having checkpoints along your route. These checkpoints where navaids or intersections determined by multiple navaids. Either way their location was known, divide the distance by the time spent travelling between them and you got your ground speed.

"it's only accurate if you're tracking exactly to or away from it" is not true, trigonometry is possible, albeit annoying.

@Sam if you want to split hairs, it's only accurate if you know your exact track and 1/cos(α) is defined where α is the angle between track and bearing. Similarly, for the checkpoint/time method, it calculates average ground speed, if you fly s-curves, it will also not be accurate.

I'm an engineer, of course I want to split hairs :P I write ADCS software for spacecraft, you don't need to explain the math.

@Sam so am I, I'm just returning the favor :)

They still teach how to calculate ground speed and wind relative to the ground by timing flight between known references in private pilot ground school (at least the one I took recently based on the Jeppesen books).

Wasn't stellar navigation a thing as well?

There's one method that has been successfully used since long-distance flights became available - you took out your map, and tried to match it to features under your plane. This allowed you to correct your course and have an average ground speed information. Obviously, this doesn't work over the ocean - it's yet another reason why ocean flights have always been tricky, to say the least.
Don't get me wrong - it isn't very reliable, it only works if you can actually see the ground and you must keep your navigation information accurate (if your navigator dozes off for an hour, it might be tricky finding your current location again!), but for a long time in aviation, it was the only thing you had. WWII strategic bombers still used this method when over enemy land (where they didn't have the assistance of a friendly ground radar).
As radar and radio communication became commonplace, it became quite trivial to track airplane positions and speeds - it's all in the "pong" you get back from the radio signal. Again, in WWII, this was used to great effect during the Battle of Britain and even later - but it only works if you have radar coverage, which usually means only over your own land and the border areas.
GPS only became available for commercial use in 1983, after a Korean Boeing strayed off course and was shot down over the USSR - GPS makes such a mistake much less likely to happen, especially over the ocean (again, oceans are tricky - usually no radar and/or features to track on your map; by the time the Korean flight could have corrected their course, they were already shot down).

According to a story I read about the SR71, planes used to be able to ask ATC for a "ground speed check", i.e. ask "What's my speed on the ground?" ATC would measure it using their ground-based radar and relay it to the pilot by voice/radio.

If you can provide some more material for us to read it would be great.
Here's a video of the pilot telling the story: Brian Shul, one of the few SR71 pilots, telling the LA Center speed story

Here's a written version (a transcript from a book): The Ultimate Ground Speed Check - Tales from the Blackbird

We listened as the shaky voice of a lone Cessna pilot asked Center for a readout of his ground speed. Center replied: "November Charlie 175, I'm showing you at ninety knots on the ground."
[...]
Just moments after the Cessna's inquiry, a Twin Beech piped up on frequency, in a rather superior tone, asking for his ground speed. "I have you at one hundred and twenty-five knots of ground speed."
. ...etc...

Wow this is good. If you can provide some more material for us to read it would be great. Not LQP.

You can always ask ATC for a ground speed readout if you're in radar coverage (it's right there in their datablock), you don'y have to be in an SR71 to do so.

Or the fastest one, anyway. The point is though, I think this was an answer to the question.

How did planes measure their speed relative to the ground before GPS?

Assuming you ask for speed determination by on-board instruments.

The ground speed is best evaluated using an inertial navigation system. The INS knows where the aircraft is currently located (latitude, longitude, altitude). By associating two measures it's easy to compute the velocity of the aircraft. IRS (inertial reference system) has replaced INS. While INS relied on mechanical gyroscopes, IRS relies on laser gyros.
The problem with the inertial units is they drift with time, due to gyroscope imperfections, Schuler loop and Coriolis acceleration. This led to accidents in the past, before they could be realigned by GPS position determination.

Note the TK/GS position of the rotating switch, to display track and ground speed instead of latitude and longitude (source)
IRS are now included in larger units that process other sensors inputs, like an ADIRU.
ADIRU (and INS/IRS) are able to compute the wind direction and intensity by comparing the aircraft heading and the actual aircraft displacement. This drift information is usually displayed to the pilot.

Ground speed and aircraft drift in the left upper corner (source)
Note that determining the ground speed is not a critical need for the crew, the aircraft must be flown taking into account the relative airspeed and the air properties (temperature, pressure, density). However ground speed is useful to predict the time of arrival at the next reporting point, or destination.
Other means:

Loran-C was a system used to compute a position and a ground speed over oceans where no DME or other VHF/UHF aids are available.
The crew relied on a sextant and celestial navigation in "ancient" times, like ships did.

Your concern is very valid.
Aircraft use two fundamentally different speeds: airspeed and ground speed. (Each of them has its own sub-species, but it doesn't matter for now). There is virtually nothing common between them, and depending on wind, you actually can have zero and even negative ground speed, or can fly 'supersonic' on a regular airliner, or climb while trying to descent. The devices to measure these speeds are also fundamentally different.
For airspeed, the aircraft use, basically, a barometer, which chamber is attached to a pipe pointed forward (Pitot tube).
And for some time, that was it. The airspeed measured this way is all you need to fly an airplane. After all, the airplane flies in the air and doesn't care about the ground (until it hits it :) The pilot would then navigate visually, by matching the map with the landscape.
On aircraft without GPS and navigational equipment (say, 50 years ago), you could get an idea of the ground speed by

Knowing the weather forecast and thus wind at every point of your intended route;
Calculating airspeed at the ground from the indicated measurements. For that, you need to take into account altitude and/or temperature. Pilots have special tools and instruments for that.

Yes, this is not an easy walk in the park, but that's part of the pilot's trade. Early airliners often included a dedicated navigator position to do such calculations along the route. And generally, it is still considered a useful skill and you need to do similar calculations when planning the route.
The next step is to use ground navigational aids and/or an onboard system that measures ground speed from the Doppler shift of the radio signal reflected from the ground. On some aircraft, the radar can do this job.
And finally, we have GPS that... no, it doesn't really measure ground speed. But it calculates it from precisely known speeds and position (with respect to grouond) of multiple satellites.

"The airspeed measured this way is all you need to fly an airplane." True, but knowledge of your groundspeed is useful if you want to do things like figure out whether you have enough fuel to reach your destination or conform to a time-based traffic separation scheme outside of a radar area.

@ZachLipton or to appease all those pesky passengers who keep asking "Are we there yet?" ;)

The Drift Meter has been used for a long time to measure ground speed.
https://en.wikipedia.org/wiki/Drift_meter

Although it's fairly unusual, some aircraft (e.g., the KC-135) are equipped to do celestial navigation. This supports computation of ground speed without external support (e.g., LORAN/VOR/GPS).
On the down side, it is somewhat time consuming, and requires both equipment absent on most aircraft, and skills absent from most pilots' repertoire.

Just to add that there were (area) radionavigation aids before GPS and these could be used to determine velocity over ground (either manually or with a computer).
The hyperbolic navigation system Gee was used in WW2 and after by the RAF. The Decca Navigator was used commercially (primarily for ships but also for aircraft, vehicles and for one job I worked on, runners).
These systems operate in a similar fashion to GPS by measuring the difference in propagation time between signals from two stations - with terrestrial hyperbolic nav, the stations are fixed and the locus of the located vehicle is an ellipse. GPS follows the same principle, except the stations are moving and at a higher altitude.
See also Loran, Omega and various short range systems.

The concept is very simple. We have an analog airspeed meter in the aircraft.
Airspeed +/- wind is ground speed
+ if tailwind, - if headwind

In the sense of "how fast are we going over the ground, right now?", its a measuring challenge. Some means of measuring successive distances to a point on the ground, or some means of measuring progress between points on the ground, is required. Before GPS, Doppler radar could read speed relative to the ground directly. DME, Distance Measuring Equipment, could give distance relative to a fixed point. Successive locations allow computing ground speed relative to the fixed point. LORAN long-range radio navigation equipment allowed location above the earth to be determined without star or sun sightings. In clouds, for example.
Before electronic tools, Celestial navigation could supply location above the earth, successive locations and times, giving ground speed. Sighting objects on the ground and measuring angles to them, or fixing the angle and timing progress between successive objects, was possible, if not very attractive.
All those give good to fair answers to "how fast are we going over the ground?"
"

The usual method is to compute your True Airspeed (TAS) and then do the wind computation to calculate Ground Speed (GS).  Computing TAS starts with pitot/static air pressure measurements, and takes altitude and air temperature into account.  You have to get the Winds Aloft from someone on the ground, by radio.
There was at least one Ground Speed measurement device out there, that I THINK used low-lower Doppler radar, when I worked on the Tracor 7800 Omega/VLF radionavigation system, back in the late 1970s.

Several ways, though none quite as accurate as a GNSS ground speed calculation
TRUE AIR SPEED, WINDS ALOFT AND TRIGINOMETRY.  Using the old, reliable E6B flight computers or by hand calcs, you can determine your true airspeed and, using the headwind or tailwind components of the winds aloft you can compute groundspeed from that.
RADAR TRACKING - ARTCC can track you aircraft's travel using a Doppler radar system.  This along with the azimuth of the radar antenna can be used to compute a groundspeed for your aircraft.
INS - Inertial Navigation Systems ar used widely in civil and military aeronautical applications where terrestrial navaids are not available.  These often use a periodic GPS update to refresh errors which slowly creep into their operation although the ring laser gyros are quite accurate and reliable.
DME - the use of Distance Measuring Equipment onboard could compute your distance to a VORTAC or VOR/DME station as well as your ground speed.  As a DME computes a slant distance, this is only accurate at times when the distance from A/c to ground station was much higher than the a/c's height above the station.  Groundspeed ccuracy was also affected if the aircraft was not flying directly to or directly from the station.
LORANS - Ah the late seventies and early eighties, when GA was in its prime and men were men - and everyone though that LORAN was the wave of the future.  Well, it wasn't; but LORAN still remains popular for maritime navigation and is still very accurate, though it is slowly being phased out.  You occasionally find older GA airplane's with a LORAN receiver in them, usually with an "INOP" tag on it.

Fly any radial towards a VOR. Turn left 90 degrees until you have intercepted another radial +5 degrees, and time the cross leg. Turn inbound again. Calculate distance from VOR. Fly 6 minutes. Repeat above procedure, except turn right back to original radial. Calculate new distance from VOR. Using 2 distances and 6 minutes inbound leg, calculate ground speed.


text:
How should I log total hours flown in different countries?
Let's say you have an EASA-style logbook with European flight time, and then, you start flying in the USA, so you buy an FAA-style logbook and begin logging hours for your flights in the USA.
I don't think it is a good practice to mix foreign hours, since if both logbooks are still open you can have inaccuracies and inconsistencies in the transferred hours.
The question is: is it mandatory to bring your flying hours from the European logbook to the "AMOUNT FORWARD" section in the American logbook, or is it optional?
What is a good practice if you have multiple foreign logbooks?

I'm curious why you would want to keep two logbooks? It seems like it would make totals and currency more difficult to track. FWIW, I learned to fly in South Africa and continued using the same logbook in the US. Instructors and examiners always comment on it and the layout is a little different, but it isn't a problem. And practically speaking, I use an online logbook for most day-to-day things anyway.

Also, in future questions be careful to target one question.  If there are a multitude of question points, post a new question for each one.

Is it mandatory to bring your flying hours from the European logbook to the "AMOUNT FORWARD" section in the American logbook?
No, it is not mandatory to bring your flying hours from the European logbook to the "AMOUNT FORWARD" section in the American logbook.
In the USA, logging time is not required at all other than information for required recent experience and check ride prerequisites.  Also, there is no reason the EASA logbook is not an acceptable document for that purpose so long as it contains the needed information such as landings.
What is a good practice if you have multiple foreign logbooks?
Consolidate them into one logbook that best fits the system in which you do most of your flying and keep only specific additional requirements for the other systems logged elsewhere.
If you need to keep the total flight hours separate, I would use one of the customizable columns that I have seen in most logbooks and label it with whichever system you fly in less.  Then you can simply subtract that column from your grand total to deduce the other system's total time.
Although, based on how much I get picked on by my German friends for not using the metric system, I could understand the assumption that we must be different.

You might want to qualify the point about "flight time is flight time". E.g. in my answer to this question I found a UK reg that says not all US flight time - specifically, PIC time - can be counted towards an EASA or UK rating.

@Pondlife 10-4 thank you!

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text:
What is the FAA's official stance on logging illegal flight time?
To preface my question, I want to discuss the reality that with the number of people and flight operations, there are surely cases where pilots have mistakenly flown under conditions in which it is not legal to do so.
Possible examples:

Students soloing after endorsement expiration.
Pilots flying without realizing their medical has expired.
Non-instrument-rated pilots inadvertently flying into IMC.
Carrying passengers without landing currency.
Acting as PIC beyond BFR currency.

Barring any discussion or speculation about punitive actions for the above listed items, what would the FAA's stance be on logged time?  Would it be logged as valid pilot time regardless of it being illegal, or does the fact that it is illegal make it null and void as logged pilot time?
For example, in the first scenario, if a student solos without a current endorsement, would it be able to be logged as PIC solo or would it not exist in the eyes of the FAA as it pertains to flight time and the flight would be considered to have been performed with a complete lack of an acting PIC?

This is pretty broad, each of those is a separate case by itself with nuances. There's no one size fits all answer.

Plus I think there are enough grey areas and judgement calls there where I think you're going to have to get it from the horses mouth by asking your local FSDO guy.

What about the pilot that flew the paying public on a Falcon business jet single pilot without a type rating in a for-hire operation without an air carrier certificate? I believe that guy went to jail. But could he have logged the time as PIC? I think the answer is no just as a pilot flying with in any other disqualifying circumstances could not log PIC. You aren't really asking about logging SIC and the regs don't speak much to logging anything else.

I'd also wonder about the possible circumstances which might motivate the FAA to try to decipher the scribbled entries in my logbook, many of which I can't read myself.

There are probably many answers, depending on the specifics of the situation. But at least one of your scenarios has a certain and definite answer.
I don't think that the FAA has ever issued a legal opinion on this topic, and I kind of doubt they would, but we might be able to piece some answer together.
But first let me address a couple of misconceptions you might have about logging time. In the title and first paragraph of your question, you simply ask about logging time, or logging pilot time. At the end, you ask about PIC or solo time. These are all different kinds of time.
You also wonder whether a pilot could log time, or does the FAA consider that flight to not have had a pilot-in-command. Those are totally different things. Logging pilot time, logging PIC time, and BEING PIC of an aircraft are all different things and don't really have much to do with each other. There are situations where you are PIC and cannot log any time. Other situations where you are not PIC and can log PIC time. Still other situations where you are PIC and can log pilot time, but not PIC time.
To determine whether you ARE ACTING as PIC, you need to look at FAR 1.1: a Pilot in Command

Has final authority and responsibility for the operation and safety of the flight;
Has been designated as pilot in command before or during the flight; and
Holds the appropriate category, class, and type rating, if appropriate, for the conduct of the flight.

That's a totally different section from the regulation that instructs you on how to LOG PIC time, which is FAR 61.51(e):

(1) A sport, recreational, private, commercial, or airline transport pilot may log pilot in command flight time for flights-
(i) ...when the pilot is the sole manipulator of the controls of an aircraft for which the pilot is rated...

In other words, BEING PIC and LOGGING PIC are completely different criteria. And those criteria for logging are that the pilot is rated, not that the pilot is current.
But there is ONE part of 61.51 that does require currency: Let's start with a student who solos after the expiration of their endorsement. FAR 61.51(e)(4) says:

A student pilot may log pilot-in-command time only when the student pilot -
(i) Is the sole occupant of the aircraft or is performing the duties of pilot of command of an airship requiring more than one pilot flight crewmember;
(ii) Has a solo flight endorsement as required under § 61.87 of this part; and
(iii) Is undergoing training for a pilot certificate or rating.

So for certain, that student cannot log PIC time.
But now, notice that this is the only place anywhere in 61.51 where currency is required. They make a point of it for student pilots but it doesn't show up anywhere else. So I would be tempted to say that a private pilot can log a flight legally that you weren't allowed to make due to currency. And about generally breaking the rules, I am tempted to add to your list: "I flew to my local uncontrolled field and made right turns in the pattern instead of left turns in violation of 91.126(b)." Do I still get to log the time, even though I flew the wrong pattern? Or what if I accidentally violated an ATC instruction? I think I still log that time. After all, making mistakes and learning from them is what "aeronautical experience" is all about.
So in that same vein, what if I flew out of currency and filed an ASRS report? What if I flew out of currency and didn't file a report? I think it's all the same; I think that breaking a reg doesn't invalidate the time.
There are some FAA opinions that back me up a little bit. In Walker, the FAA gives an opinion about a non-instrument rated pilot who manipulates the controls of an airplane in IMC. Because that pilot is manipulating the controls of an airplane in which they are rated, they log PIC time according to 61.51(e)(1)(1). In that opinion, the flight is legal because their instrument rated friend is occupying a pilot station and acting as PIC (But the friend doesn't log time, even though they are PIC, because they are not manipulating the flight controls).
Perhaps more importantly for your question, that pilot also logs instrument time according to 61.51(b)(3)(2) because the time was acquired in IMC. So a non-instrument rated pilot CAN log instrument time, without a CFII on board, even though he has no instrument rating.
So I think that in general, inadvertently breaking a reg doesn't affect logging, but that is different from saying that such a flight is a very smart or safe thing to do, and if you do log it, you're admitting to a violation in an official record. Also not smart.

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Why does 14 CFR have skipped subparts as seen in the ASA 2019 FAR/AIM book?
As an example, part 91.101 skips every even number until 91.126.
Why are they not in sequence as 101, 102, 103, etc?

Some of them were renamed/reorganized in 1989 based on proposals/petitions by the AOPA (referenced in FSIMS).
91.102 became 91.143 Flight limitation in the proximity of space flight operations.
91.104 became 91.141 Flight restrictions in the proximity of the Presidential and other parties
91.106/108/110/112/114 did not exist
91.116 became 91.175 Takeoff and landing under IFR
91.118/120/122/126/128 did not exist
The "did not exist" ones are probably proposed legislation that was removed prior to it being introduced into the Code of Federal Regulations, or regulations that were removed earlier (I can't find an older version of the CFR to check).

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text:
What criteria are used to classify an airport as a satellite airport?
The AIM discusses services provided to satelitte airports of class C airspace.
What determines whether an airport is considered a satellite? Distance, private or public classification,  etc?

I'm not sure there's "criteria", its just a close proximity airport where IFR procedures require the assistance of ATC. VFR pilots don't really talk to the governing airport. I don't believe any private airfield is a satellite airport.

I have always thought that satellite airports were those that were either in Class C airspace at the surface (i.e. with 5NM of primary airport) or under the shelf of Class C (i.e. within 10 NM of primary airport)

@wbeard52 I know what you mean, and you're kind of getting at the ambiguity I'm trying to resolve.  What if an IAP for an airport well out of the class C airspace cuts into the class C?  Would that automatically make it a satellite airport?  Is it any airport within the 20NM range where radar service is provided?  I don't know.

The answer is found in §91.130 and AIM 3-2-4.
A satellite airport is any airport under the class C shelf outer are of 20NM.

§91.130   Operations in Class C airspace.
(a) General. Unless otherwise authorized by ATC, each aircraft operation in Class C airspace must be conducted in compliance with this section and §91.129. For the purpose of this section, the primary airport is the airport for which the Class C airspace area is designated. A satellite airport is any other airport within the Class C airspace area.
(b) Traffic patterns. No person may take off or land an aircraft at a satellite airport within a Class C airspace area except in compliance with FAA arrival and departure traffic patterns.

What does Class C airspace area mean?

AIM 3-2-4 Class C Airspace Sub Paragraph 3 Note 4
Though not requiring regulatory action, Class C airspace areas have a procedural Outer Area. Normally this area is 20 NM from the primary Class C airspace airport. Its vertical limit extends from the lower limits of radio/radar coverage up to the ceiling of the approach control's delegated airspace, excluding the Class C airspace itself, and other airspace as appropriate. (This outer area is not charted.)

I believe the answer above is correct.  There is also another way of looking at it.

§71.51   Class C airspace.
The Class C airspace areas listed in subpart C of FAA Order 7400.11D (incorporated by reference, see §71.1) consist of specified airspace within which all aircraft operators are subject to operating rules and equipment requirements specified in part 91 of this chapter. Each Class C airspace area designated for an airport in subpart C of FAA Order 7400.11D (incorporated by reference, see §71.1) contains at least one primary airport around which the airspace is designated.

That document shows the boundaries of Class C Airspace Area and does not include the outer area.

ASO SC C  Myrtle Beach, SC Myrtle Beach International Airport   (lat. 33°40'47"N., long. 78°55'42"W.)
That airspace extending upward from the surface to and including 4,000 feet MSL within a  5-mile radius of the Myrtle Beach International Airport, and that airspace extending upward from 1,200 feet MSL to and including 4,000 feet MSL within a 10-mile radius of the Myrtle Beach International Airport.  This Class C airspace area is effective during the specific dates and times of operation of the Myrtle Beach Approach Control facility, as established in advance by a Notice to Airmen.  The effective date and times will thereafter be continuously published in Airport/Facility Directory.
AMENDMENTS  03/27/97  62  FR  6698  (Added)

Since the information from the FAA conflicts with one another, I would ask for a legal interpretation.


text:
Do all airplanes have the same turning radius when operating under the same conditions regardless of size and weight?
Would any airplane in coordinated, turning, level flight have the same turn radius at a given combination of no-wind ground speed, bank angle, and density altitude as another airplane of significant difference in size and/or weight?
For example, if a small airplane and a super heavy airplane could match speeds at the same density altitude, and they both held the same bank angle while holding altitude, would they generally be expected to have the same turn radius if they weren't slipping or skidding?
If yes, what are some examples of exceptions to this if any?

Take the no-wind case for simplicity.  For a given bank angle, and a given groundspeed (airspeed), there is only one turn rate that will center the slip-skid ball, so the answer to the question must be "yes", assuming that "coordination" is being defined in relation to the slip-skid ball and not some other instrument such as a yaw string.
Due to various interesting aerodynamic effects that happen when an aircraft's size is significantly large in relation to the turn radius, flying with the slip-skid ball completely centered will not always be completely optimum.  Similarly, the answer to the question would be different if the question were to specify that "coordination" were to be measured in reference to a yaw string or other similar instrument located at some given point on the aircraft, rather than a slip-skid ball. For more, read "Circling the Holighaus Way" by Richard Johnson.

I could go into the flying-by-reference-to-yaw-string case in more detail but am inclined to leave that as an answer to a separate question, should one be asked--


text:
May an instrument instructor log instrument approaches that a student flies in simulated conditions as approaches for currency purposes?
There's rumor that a former DPE claimed that a CFII who is providing training to a student can log that student's simulated instrument approaches as the instructor's approaches for currency purposes.
That didn't sound like it could be true, so I asked him if he could provide a written source to back it, but he could not.

So, is it true?  If so, can you please provide a source to prove it in your answer.
Common sense would tell me this is not true because the instructor is neither flying the plane nor logging instrument time.
Does it make any difference if the approach is simulated instrument in a flight simulator or FTD in which neither the instructor nor student have reference to anything but instruments?

Related

It depends on the conditions.
For actual conditions:
The FAA addresses this in this letter of interpretation: (see full letter for the whole explanation)

QUESTION: Am I correct in understating that a CFII may log approaches
  that a student flies when those approaches are conducted in actual
  [IMC]?
ANSWER: Ref 61.51 Yes, a CFII may log approaches that a student flies
  when those approaches are in actual [IMC].
...
The Chief Counsel's office agrees that the earlier guidance reflects
  the appropriate interpretation of the regulation.

For Simulated VFR conditions:
If the student is flying under the hood in VFR conditions the Instructor may not log in the time also based on 61.51. Instructors may only log instrument time in actual conditions.

(g)Logging instrument time.
(1) A person may log instrument time only for that flight time when
  the person operates the aircraft solely by reference to instruments
  under actual or simulated instrument flight conditions.
(2) An authorized instructor may log instrument time when conducting
  instrument flight instruction in actual instrument flight conditions.
(3) For the purposes of logging instrument time to meet the recent
  instrument experience requirements of § 61.57(c) of this part, the
  following information must be recorded in the person's logbook -
(i) The location and type of each instrument approach accomplished;
  and
(ii) The name of the safety pilot, if required.

Most GA sims I have encountered can only be used by one person at a time. The CFII is there to observe and advise but cant really "take over"

(4) A person may use time in a full flight simulator, flight training
  device, or aviation training device for acquiring instrument
  aeronautical experience for a pilot certificate or rating provided an
  authorized instructor is present to observe that time and signs the
  person's logbook or training record to verify the time and the content
  of the training session.

After section (4) that is block quoted, the latest version of the regs also has, "(5) A person may use time in a full flight simulator, flight training device, or aviation training device for satisfying instrument recency experience requirements provided a logbook or training record is maintained to specify the training device, time, and the content." -- No instructor required, but your ultimate point is that an instructor isn't going to take over for safety in a SIM.

Sounds like the answer is, no.  It is not true.

Note that it has to be an FAA-approved sim or training device. You can't just fire up MS Flight Simulator and log that as currency time.


text:
What are approach control's expectations regarding weather information for flights to satellite airports?
I have never passed through class-C airspace without intending on landing at the primary airport.
If the flight is conducted under VFR, and I am planning on landing at a satellite airport to the primary class-C, will approach control expect me to indicate that I have ATIS information from the primary airport, that I "have numbers" for the satellite airport landing destination, or that I have both weather station information sets?
What about just passing through their airspace with no intent to land nearby? Do they still expect that you indicate receipt of ATIS information?

I've always found that upon contacting ATC in class C with my intentions they will ask me if I have the latest ATIS, and if I say no, they'll give me the altimeter and winds. Usually contacting ATC goes along the lines of "Approach, Skyhawk 12345 inbound to land KABC with Lima"... If I leave out the "with Lima" part they will either ask me or just give me the current altimeter/wind.

So is the landing destination pretty much irrelevant in that regard?

I'm not sure in which regard you are referring to but it boils down to the pilot being responsible for having the information required to land in or transition the airspace. The only time I'm sure you are required to report having the numbers is for an IFR flight plan, VFR is mostly a courtesy reminder by ATC. You should be updating your ATIS info along your flight route anyway regardless of where you land.

I fly out of a controlled satellite class D (KLOU, Bowman Field) below a class C (KSDF, Louisville International) so I'm fairly familiar with this scenario, at least in the way that it's handled there. The short story - in my experience - is that Approach only cares about you having the numbers or ATIS for the airport where you'll actually land.
First the theory. The ATC orders say:

7−1−3. APPROACH CONTROL SERVICE FOR VFR ARRIVING AIRCRAFT
Issue the following where procedures have been  established for
  arriving VFR aircraft to contact approach control for landing
  information:
a. Wind, runway, and altimeter setting at the airport of intended
  landing. This information may be omitted if contained in the ATIS
  broadcast and the pilot states the appropriate ATIS code or if the
  pilot uses the phrase, “have numbers.”

Note the "airport of intended landing", they aren't going to pester you to get the ATIS for somewhere that you aren't going to.
Second, the practice. If I'm inbound to KLOU on flight following (don't leave home without it!) then my first contact with Louisville Approach usually goes like this:

Me: Louisville Approach, N12345 level at 6500
  Appch: N12345, roger, Louisville Altimeter is 2992, report when you have the weather at Bowman, information Kilo is current
  Me: N12345 has Kilo at Bowman
  Appch: N12345, roger [and further instructions as needed]

As a controlled field, Bowman has ATIS, not "the numbers" but I've had more or less the same exchange at other places.
I think that Ron's comment about information is useful here: when I'm inbound I usually have both the KSDF and KLOU ATIS anyway, just in case. Also notice how the KSDF controller helps me: the KLOU ATIS could have changed from Kilo to Lima between the time I got it and the time I called Approach. By telling me that Kilo is current, the controller is effectively telling me if I have to go and get the ATIS again or not.
As for just passing through class C, the very few times I've done that ATC has simply given me the local altimeter setting and that's it. I'm not landing, so they don't seem to care if I have the ATIS or not.

It great if you want to listen to the non-landing-airport ATIS for situational awareness, but we don't need you to. For both VFR or IFR, we will issue the general area altimeter setting and confirm you have the current ATIS at the landing airport. For an uncontrolled airport (no ATIS) we will confirm that IFR arrivals have "the weather" but this is not required for VFR arrivals.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
How does a C208B's climate control system that utilizes bleed air for cabin heat work?
I'm studying the systems on my first turbine-engine aircraft, specifically, a C208B.
I know that there is "bleed air heat" that mixes with re-circulated cabin-air.  I know that the bleed air is compressed, and thus hotter than it would be in an ambient pressure.  I also understand that if the compressed air were decompressed it would return to its original temperature or lower due to entropy in the compressed state.
Do these systems utilize heat exchangers much like a car's A/C system except they warm the uncompressed air entering the cabin and cool the compressed bleed air through a heat exchanger?  Surely they cannot send actual bleed air directly into the cabin and have it remain hot because it would immediately decompress, right?
How do these systems typically work?  How is it different between an uncompressed unpressurized and compressed pressurized cabin?  I would think even a pressurized cabin would not retain enough internal pressure to maintain anything close to the heat level of the compressor air.

See "air cycle machine" on wikipedia for an explanation of how these things work.

Heat though, not air conditioning.

If you expand compressed air via free expansion it will cool down only a bit (ideal gas wouldn't cool at all), not nearly back to the initial temperature—because you are not extracting the energy expended to compress it, and the temperature is proportional to the internal energy.

There is lots of detailed information available on how these systems work, but in general once bleed air is tapped off the compressor section the lines split:  One line stays hot, and the other runs through a heat exchanger to extract as much heat energy as possible.
From there the cooler, pressurized bleed air is expanded.  However, because it was "pre-cooled" in the heat exchanger it does not resume its previous temperature, but instead becomes cold refrigerated air.
Then, (just like your kitchen faucet...) a mixer combines the refrigerated air with the hot air to a tolerable temperature as selected by the crew, and vents it into the cabin.
The temperature control principles are the same whether the aircraft is pressurized or not, but there are additional seals and valves needed to maintain and control pressure.
Regarding the expansion and loss of pressure, the compressor did not just reduce the volume, but added velocity which was turned into more pressure by the stators (energy came from the fuel).

Does a non-pressurized C208B have a full ACM though? It does not need to pressurize and if it only has heating, not air conditioning, it may just free-expand a bit of bleed air.

My answer wasn't specific to the Caravan, because although it was mentioned in the question, I interpreted it as a more generic question about heat exchangers on turbine powered aircraft.  But you are correct, the 208 doesn't have the same kind of AC packs as pressurized planes.  In fact looking in the manual, it doesn't even have a heat exchanger unless you count the fuel heater that pulls a little heat out of the bleed air.


text:
At what Mach number does a fan jet become more efficient than a turboprop?
Dynamic pressure is based on air density and the true airspeed of an aircraft.  As one climbs, indicated airspeed can remain constant as true airspeed climbs, resulting in only minor changes in Reynolds number (therefor performance) until critical Mach number is approached.
This was shown in 1937, when a biplane flew to over 50,000 feet.
However, a propeller must spin faster and increase its pitch as True airspeed increases and air density decreases.  Fans are already supersonic and seem to suffer less by increasing RPM.
Although turboprops are clearly more efficient lower and slower, is there a "cross-over" point where it is more fuel efficient to have a fan jet engine in terms of thrust per gallons of fuel consumed/second?
At what Mach and altitude would this be?

That's an interesting topic. I want to know the answer too. I'm also curious how that 1937 biplane flew so high. I thought piston engine can't do that.

@crow, power of both piston and turbine engines declines with density altitude in approximately the same way, so reaching a high altitude is a matter of installing a sufficiently powerful engine so enough power is left even with the low air density up high (often then you are not allowed to open the throttle or fuel valves to full down low, because the engine isn't designed to handle the torque or temperature it would produce in the dense air).

@Jan Hudec, Thanks man. So my "understanding" of how piston engine works is actually just how it normally worked with common airplanes.

@JanHudec But you also need dense enoug air for a propeller. There must be some air for the propeller to use, not just for the engine to work, otherwise the aircraft couldn't fly. The Caproni was close to the altitude limit for piston-driven props. The altitude record for a manned piston prop is the Grob Strato 2C's 60,900 ft.

@HiddenUser, both a propeller and the ducted fan of a turbofan or even a turbojet need the air to produce thrust. The jet has a bit of advantage in being able to generate higher delta-V, but since that reduces the propulsive efficiency, and the shortage of air limits the power, it does not help all that much.

From Torenbeek, Synthesis of Subsonic Airplane Design. The graph compares Thrust Specific Fuel Consumption of jet engines with [quote from the book]:

C$_P \cdot$V / $\eta_{prop}$, where V is the flying speed, C$_P$ the specific fuel consumption related to the shaft horsepower and $\eta_{prop}$ the efficiency of the propeller.

This is a 1980's graph for Mach and altitude at cruise condition, comparing aeroplanes optimised for their missions with existing technology. It reveals the following:

Propeller aircraft are the most fuel efficient, until compressibility effects around the tips cause large losses. The graph is a generalised one, propellers designed for high sped with swept tips hold their fuel efficiency advantage over a larger speed range.
Turbine engines are slightly less fuel efficient than piston engines, however they scale up better, have lower weight and burn kerosene, not aviation gasoline.
At higher subsonic speeds the bypass engine (the turbofan) is the most fuel efficient. Depending on the bypass ratio, $\lambda$ of > 10 is no exception nowadays.

So comparing conventional props with conventional turbofans, the cross-over point for fuel economy is between 0.4M and 0.55M. It can be seen that the open propeller is much more efficient than the shrouded fan before the compressibility starts to play a role, and therefore there has been over half a century of research into propfans.

The pic above (from the wiki entry for propfans) shows an open dual-disked fan, each with 8 swept blades in order to delay compressibility effects. Which will shift the crossover fuel efficiency point to higher Mach numbers.

However, a propeller must spin faster and increase its pitch as True airspeed increases and air density decreases.

Not for constant-speed propellers, which only change their pitch when true airspeed varies.

Much lower crossover than I thought!  Could enclosing the fan in a duct (possibly lowering incoming airstream velocity and increasing pressure as a ram) be helping the fanjet? (as compared to a prop spinning in the freestream).

There has been over a half centurt research in unducted fans, but the noise remained the main problem. The research kept on trying because of the increased fuel efficiency of unducted fans.

The graph indicates that standard props are better at lower Mach numbers, until the compressibility effects start playing a role. Change the shape of the prop, and the compressibility effects are delayed to a higher M.

Safran is showing an updated version of 'Propfan', 'UnDucted Fan', UDF, they call it 'Open Rotor', see image.

Attached chart is from book by Hovey 'Ducted fans for light aircraft and homebuilt'.
The concept of propulsion enclosed in a duct is having interest today.
Blessings +

Can you confirm the "propfan" set up is contra rotating?  Also, we aren't looking low end airspeeds, and somehow $ducted$ $fans$ do very well at higher Mach.  I suspect that the back prop may be doing a higher percentage of "pushing" at speed, the front blades may be sending a pulse of more compressed air into them.  I am wondering if the duct acts as a ram, with the same effect, at higher Mach.  Essentially, pre-compression may give the prop (or fan) more to "bite" into.

Thanks for your interest. Let them talk about me, even if it's badly. Sorry, I have no more info, even if SAE member, I'm not engineer, but videos about PropFan show it is contrarotating. Blessings +

Your answer is certainly helpful. Thanks.


text:
Is it possible to fly VFR above the IMC floor or VFR-On-Top without a specifically filed route, both using an IFR flight plan to go through IMC?
*Note, I'm not trying to recommend this, but I am curious if it can be done.
In this question, Steve V.'s answer made me wonder about this:
One time during my commercial training, my instructor and I received an "area clearance" over downtown Nashville for simulated aerial photography, which allowed us to circle over downtown with visual reference within class C airspace as we wished with no defined route.
In the above case, we were not on an IFR flight plan, nor were we above the IMC floor.
Scenario 1:
Is it possible to get an IFR clearance for an area as VFR-On-Top, without having to file a routed flight plan with fixes, effectively allowing an instructor and a student to practice with their own spontaneous navigation choices in VMC at an altitude above IMC conditions?

Scenario 2:
Same as above, but foregoing the VFR-on-top and accomplishing it purely as IFR.

Scenario 3:
File two IFR flight plans, cancel the first one once above clouds in VMC, do your thing, and then receive the next IFR flight plan clearance to shoot the approach back down.

Are any of those options?

Related

I would like to emphasize the part about utilization of an IFR flight plan to fly through a layer of IMC.  I am not referring to flying around and above clouds.

This question probably covers some of your points but here's some more information. See the AIM 5-5-13 and ATC Orders 7-3-1 for more details.
Can I get an IFR clearance for an area and operate there VFR-on-top?
Yes. VFR-on-top by itself is only a clearance to use VFR altitudes, it isn't a clearance to deviate from your course. But ATC can clear any IFR flight to operate within an arbitrary, defined area (ATC Orders 4-4-1):

EXAMPLE−
  1. “Cleared to fly east of Allentown VORTAC between the zero four five and the one three five radials within four zero mile radius.”
  2. “Cleared to fly east of Crystal Lake radio beacon between the two two five and the three one five courses to Crystal Lake within three
  zero mile radius.”
  3. “Cleared to fly northeast quadrant of Philipsburg VORTAC within four zero mile radius.”

Same as above, but foregoing the VFR-on-top and accomplishing it purely as IFR.
I don't know exactly what you mean here: VFR-on-top is an IFR clearance. If you're asking how to change altitude as needed under IFR without using VFR-on-top, you can request a block altitude clearance.
Can I file two flight plans?
What would the departure point be for your second flight plan? I suppose it might happen if you departed IFR, requested climb to VFR-on-top, cancelled IFR in VMC, then called back for a pop-up IFR clearance to shoot an approach. But I don't see the point: why not just work with ATC in the first place and stay in contact with them for the whole flight?
All in all, the simplest thing here is just to ask ATC for what you need. Except in very busy terminal areas, they're very good at accommodating pilot requests, whether VFR or IFR.

file and depart IFR, then cancel when the weather improves along the route. get a pop-up to make the approach. happens in the SF Bay Area all the time

You can file to/from navaids or fixes, not just airports. This is a perfect example of when that could be useful.

@Pondlife regarding the distinction of VFR-on-top vs. not I was just asking for confirmation that as far as ATC is concerend, there's really no difference regarding the pilot's ability to request an area clearance with a block altitude under either clearance (with or without VFR-On-Top).  Great answer. Thanks.

@Pondlife regarding the second IFR flight plan, I figured one could file a composite flight plan that becomes IFR at some nearby fix such as a VOR.  Definitely sounds like more work than it's worth though.

@Ryan Mortensen, I'm not sure I understand your last comment.  Do you think filing a composite flight plan is more work than filing two separate IFR flight plans?  In practice the composite plan is very easy to both file and execute.  I could add more detail to my answer below if you aren't sure how it works.  P.S.  I agree with everything Pondlife says above, and it sounds like you have some familiarity with a composite plan since you mention it...

What you are asking about is done all the time in the military:  IFR to a fix that defines a MOA entry or Low Level route, a VFR leg, then an IFR return.  Look up "Composite Flight Plans".
The effect or result is very similar to your scenario 3, but it is all done on one flight plan.  Since your middle leg route will be spontaneous, just file for a 30 minute delay for the VFR portion.


text:
Why would an airport be depicted with symbology for runways longer than 8,069 feet even though it is reported on the sectional as 7,200 feet?
This airport, KMKO, Muskogee-Davis Regional in Oklahoma southeast of Tulsa is depicted on the sectional chart with symbology normally reserved for airport with a hard surfaced runway longer than 8069 feet, but this one is only reported on the sectional as 7200.
Is this a mistake by the FAA or is there some clear explanation about why this is?


text:
What is the expected time frame for FAA knowledge test results to show up in IACRA?
I just passed my Part 107 Remote Pilot's knowledge test this morning, and I noticed that IACRA indicates it may take up to 48 hours for the test records to show up.  Does it always take 48 hours or is it sometimes faster than that?  What is the soonest that I might reasonably expect the test results to appear?
Bonus points if anyone knows why it takes so long, but I realize that may not be something anyone knows about (or can talk about).

Mine went through at about 35 hours after I finished the test.  Now to see how real the 7 days for the temp cert is.

I passed back in December 2016.  Took 3 days to get temp license and about 90 days to get my perm license.  Took me a week of study watching Youtube videos on weather and sectionals, in conjunction with UAS107 prep app (https://play.google.com/store/apps/details?id=uas107.openrobotix.labs&hl=en)

Do you recall how long it took for the test to be available in IACRA so you could process the application.  I was able to find pretty good info on timings for the rest of the process, but nothing on when I should expect the test itself to show up.  Trying to avoid trying again every few hours if it's going to take a while.


text:
Should I log flights on separate lines if I park the plane between legs to different airports?
I flew one leg of a cross country, landed, parked, and turned off my engine. I flew the same plane home an hour later.
Are these two separate flights and should be logged as such, or can they be logged together on one line?
Is there any rule that states how it should be logged?

Welcome to aviation.SE! Which country or regulations are you asking about?

If your question is about the US then it may be answered here.

The question this is marked as a dupe of asks if stopping short of 50NM before continuing would make the flight over 50NM in total become “not XC”.  This question asks if multiple legs with shutdowns in between need to be logged on multiple lines. Not the same at all.

Is there any rule that states how it should be logged?
No, there isn't, not specifically regarding exiting the aircraft at your destination and getting back in later that day.
You can log it on one line and simply enter in the remarks, "broke for lunch at destination", or some similar comment if you want to remember what you actually did.
No one will mind whether you choose to log your return separately.  Personally, I would use one line simply for less writing.

There are no hard and fast rules in the US about how and when to break up a flight like this, so do what makes the most sense to you.
In the military I would generally log individual sorties on different lines because there were varied mission codes, and sometimes we switched crews.  However, on a multi leg cross country I would log it all on a single line.  (As long as the multiple legs occurred on the same day.)

Aside from personal logs, in Canada there is a Journey Log that stays with the airplane where you enter each flight separately with dep/dest air time and flight time etc.  I've always wondered how you track hours on a US ac when the only logs for the airplane are the tech logs.

@JohnK For GA piston airplanes, the maintenance logs use tach time. AD compliance and 100 hour inspections are based on tach time. I don’t know how they do it in the turbine world. Rental airplanes sometimes have a Hobbes meter and I sometimes see Hobbes time in the logbooks but it is just there for completeness/cross checking.

We have a Hobbs in the Caravan.

@JScarry as it happens when I make Journey Log entries for my plane, I don't record the actual clock time, I use the tach reading for the air time (compliance requirements are also based on air time, so it works out the same in the end) and add a tenth for the flight time.  If I had a Hobbs, I'd use it for the flight time.  Years ago the Journey Log format included up and down clock times you were supposed to record, but it was simplified and now it's just air time and flight time and total air time.  The best feature of the Journey Log is when you buy an airplane you know where it's been.


text:
Is there currently a measurable shortage of pilots?
Is there a clearly identifiable and measurable pilot shortage right now? If so, is it a shortage of pilots or of captains, i.e. more experienced pilots? Are airlines changing any personnel rules - like time to go from first officer to captain - that would imply there is a pilot shortage?
If any shortage is for captains couldn't airlines 'upgrade' first officers to fill the places? But presumably that would create a shortage of FOs in turn.

Who says there's a pilot shortage?

Ok, for those that don't want to answer...just don't waste your time. Cheers.

Yes there is a pilot shortage but mostly experienced pilots, go have a look at all the recruitment sites...captains are urgently wanted from the middle east to asia..

If there is a shortage then the cost of pilots will increase. If pilot salaries, paid benefits, paid training, paid holidays etc. are increasing, then pilots are in increasing demand. That's probably the clearest way to identify a shortage. In theory airlines in one country could handle a shortage without increasing wages by importing pilots from other, cheaper countries - i.e. increasing the supply - but that should also be identifiable somehow, e.g. more working visas issued to pilots.

mizzu, it isn't that people don't want to answer, but rather that your question is too broad to have an actual definitive answer.  As the first comment on  your question asks, Which country are you even talking about?  As he also says, our site is not designed or intended for open ended discussions, but rather for questions which can have a rather specific narrow definitive answer (Aviation SE is not a forum, but rather a Q&A site).  Please read [ask] and look around our [help] for more info. This site is a great resource, but is for a different purpose than what you may be used to!

"Yes there is a pilot shortage": If you're not under a NDA, maybe you could share your source to make the question less open.

@Federico although badly phrased (ie as opinion/discussion), this is a question with a quantifiable, reference-able answer. Perhaps worth cleaning up the question to make it less inviting of opinion, but I do think it's valid

@JonStory my comment was on the original version. the current version is already a much better one.

Ah my apologies - the mobile app doesn't make edits as clear so I hadn't spotted it had already changed

Here in the US (because this varies around the world) some sources do say there is a pilot shortage. There are many reasons that have been cited for the decrease in pilots here in the states. But the main points seem to be,

Rising Costs of training
FAA upping the required hours (250 -1500) for a full ATP ticket
Lower conversion from military pilots (there was a time when many of the commercial pilots out there were former service pilots)
Lower Salary Prospects: its no mystery that pilots don't make what they once did nor get the perks they once did.

Another factor that effects this once you are in the industry is the fact that "seniority" does not transfer over from airline to airline. Generally this is not an issue if you work for someone like American or Delta who have plenty of jobs and steady routes. But if you are captain at NotSoWellEstablishedAir and they go belly up you will most likely join one of the others lower in the ranks if not at the bottom.
Another thing that is worth mentioning is that it may be more advantageous for a pilot to remain a very senior first officer instead of becoming a very junior captain. You may have more power over your route choice, time off, and general schedule as a senior first officer than as a newly minted captain. For some pilots, like those who may be trying to start a family this may be seen as an advantage.
As for the shortage over seas (outside the US) that stems from different issues. First and foremost many countries have seen great and more importantly fast economic prosperity which has allowed them to get into the aviation game. A game traditionally filled with high costs and heavy regulations. As such many newly wealthy nations have been able to enter the aviation world much faster than their regulations and training programs can keep up with. The FAA is almost 60 years old with aviation regulations dating back to the 30's with the CAA. There are even some american issued pilots licensed signed by the Wrights them selves from the very early days. Other countries simply don't have the history of growing with aviation like the US and similar countries have had. Thus they have all these new planes but no one to fly them and no well established programs and regulations to create the pilots. In turn they are forced to import trained, certified pilots from elsewhere.

Wasn't the reason for increasing the requirement a huge surplus of pilots leading to absurdly low wages for F/Os on regional airlines? (Note: they didn't change requirement for ATPL, they changed the requirement for F/O to need full ATPL)

I'll put it this way: There wouldn't be a pilot shortage if the pay was right and regulators would stop putting in place roadblocks to professional airline pilot training like the asinine 1500 hour rule for first officers.
The saddest thing about this nation's corps of professional pilots is that it's a profession of people who absolutely love what they do and are exploited and treated as wage slaves by company brass who know this.
At this point, though, things are beginning to change in the USA.  The airlines are faced with a glut of senior captains over 65 now and forced to take mandatory retirement.  With typical starting salaries for regional FOs being about \$18-\$22k based upon a realistic calculation of pay, being on duty for 14-16 hours a day, and forced to live in crowded apartments with several other pilots, it's no wonder that people pursuing a career as a professional pilot have dwindled.  This in contrast with the rising demand for pilots has created a situation where the airlines have no choice but to act.  Salaries are being increased, and many airlines are adopting their own flight training programs where they cover the costs to train promising candidates in exchange for a mandatory employment contract for an agreed upon length of time (usually about 7 or so years).

Sure.  The mandatory requirement for 1500 flight hours was a direct result of the crash of Colgan Air 3407, in Buffalo.  The NTSB lists the official cause of the crash to be the Capt. Renslow's inappropriate response to the stick shaker leading to aerodynamic stall of the airplane.  It also lists crew fatigue as one of the major factors leading to the crash as well.

I'm sorry but that is your opinion, not what I have asked. I'll rephrase: is there any study that shows that the 1500 hours requirement is detrimental or does not provide any benefit? Because if we have to bring opinions, I could argue that inappropriate responses can be a product of inexperience.

Accidents are caused by event chains; if one link fails, there is no accident.  Here you had 1) A low time CAPTAIN with mediocre aptitude at airmanship 2) an ill first officer 3) both are exhausted and fatigued from a long duty shift, which the FO comments there were no other viable financial alternatives for her (See the CVR transcript).  4) Both crew were paid less than 30k annually, limiting their living and commuting options further.

Combine all of this together and you have a ripe situation for a flight crew not paying attention to airspeed on final, then making a rookie mistake with a heavy twin, causing the stall and crash.

Sorry on the delay; the response is limited to about 700 characters; I need more than that to fully answer the question.

Now the 1500 hour rule for FOs was never a requirement in the past and to the best of my knowledge was never a contributing factor to other air transport accidents.  It hurts the industry by delaying the amount of time for new pilots to get a FO seat, forcing them to do flight instruction then possibly cargo hauling or some other means to earn hours for 2-4 more years after earning their wings.  As I said, it's just a asinine impediment, with little or no benefit for the airlines.

You make a reasonable case, but it's still your opinion. We try to give answers that are factual and supported by sources and studies, rather than opinions. Also remember that the question is about whether there is a pilot shortage, not the causes of it.

You don't need a double-blind study with 50TB of analysis to know that the new rules to little to enhance safety.  The burden lies with the regulators to produce compelling evidence that high time minimums will improve flight saftey.  My observations lead me to the conclusion that arbitrary hour minimums have not translated to higher a quality of pilot.

My opinion is supported by the evidence in the NTSB report on that crash.

This is a Q&A website. Your post does NOTHING to answer the question.

Yes it does answer the question.  It says that a pilot shortage does exist and is directly correlated to the fugitive nature of the business, low pay, strenuous working conditions, long hours, and brueaucracy interfering with the process of hiring new pilots.


text:
Do cockpit panels have an indication that oxygen masks in cabin have been deployed?
Do cockpit panels have an indication that oxygen masks in cabin have been deployed for Pilot information?

Yes, there is an indicator for passenger oxygen status.

(Image Source: www.b737.org.uk)

That panel looks like it has just been bolted on as an after thought.. Was a different display there before hand?

@superphonic: All the panels look like that!

@superphonic: Perhaps overlays with different languages. Only the text is bolted on.

@LightnessRacesinOrbit Seems plausible.

In addition to SentryRaven answer, this is the same for Airbus (A320):

(source: FCOM A320 at SmartCockpit.com)


text:
What is a "departure" in the context of flight testing / maneuvers?
I was reading about the F-35 flight tests and it mentions a "departure" at a couple of places.
What does that word mean in this context? I understand spins and stalls but what's a "departure"?

AF-2 was the first F-35 to be flown to 9g+ and -3g, and to roll at
  design-load factor. Departure/spin resistance was also proven during
  high angle-of-attack (AOA) testing which eventually went as high as
  110 deg. AOA
Pilots really like maneuverability, and the fact that the aircraft
  recovers so well from a departure allows us to say [to the designers
  of the flight control system laws], ‘you don’t have to clamp down so
  tight,

(Wikipedia Lockheed Martin F-35 Lightning II article)

Expanding on the other answer...
A loss of controlled flight (departure) is what happens when the aircraft is moving in an uncontrolled manner (on any one or all axis). For example in the video that the other answer linked, the departure from controlled flight happens when the aircraft exceeds its operating envelope and begins uncommanded movement in any axis, in this case when the pilot yanks back on the stick and the aircraft yaws uncommanded (like a "boot full of rudder" as the person in the video comments).
This is why an aircraft can depart controlled flight in individual axis while retaining control in others. You can intentionally make an aircraft depart controlled flight (spin for example) and if the control surfaces still have enough authority, it can be recovered (altitude withstanding). You aren't really "in control" but you are coaxing the aircraft back into the flight envelope.
If you don't have enough control authority to get back into the flight envelope, or altitude, this is otherwise known as a crash... Some aircraft cannot be recovered from maneuvers like spins (Cirrus SR-20/22 for example, not certified to at least).
So, controlled flight is defined as providing control inputs without uncommanded movement on any axis (significant, for example just using ailerons may result in yaw). Any departure from controlled flight is uncontrolled flight, even if you regain control later.

Very interesting, thanks. So if an acrobatic aircraft or military craft executes a spin is that still uncontrolled flight?i.e. Are there planes which can be in a spin & still be in controlled flight?

Isn't it mighty hard to deduce from a crash whether there was control authority or not enough to return to the envelope because that will also be a strong function of what sort of inputs, in what sequence & of what intensity / duration were provided to the control surfaces by the test pilot? At  a time which I'm  pretty sure is very stressful even for a test pilot?

I think you are extrapolating any crash to mean a departure, when typically I'd say a majority of crashes are "controlled". Either CFIT (controlled flight into terrain), fuel outages, flying into IMC, etc. But yes, its very hard to determine that, but typically test aircraft have a LOT of telemetry on them and the inputs can be recreated against mathematical models to see exactly where the aircraft was in the flight envelope, even during crashes. Usually test pilots are chosen because they have a high ability of doing the right thing in stressful situations.

And to answer your first question, yes I'd consider any aircraft, military or civilian that does a spin to be a departure from controlled flight, even if control is regained. Acrobatic aircraft depart flight into a spin in such a manner that its "cool to watch", but I don't think it degrades from it being a departure in the basic sense. Since a spin is where one wing is stalled more than the other, I'm not sure you can say that any aircraft is both in controlled flight and a spin. See this link for good reading on spins

Is there a possibility, of having the Control System Logic itself provide the right inputs to return a plane into the Flight Envelope after a departure is detected or indicated by the controlling pilot? i.e. Is it possible to algorithmize the stick inputs that are needed to return a flight into its envelope assuming control authority exists? Can a flight computer can apply these inputs faster & more reliably than a human pilot?

Yes, these types of protections are called alternate law/mode control algorithms and many commercial systems have them to avoid departing in the first place. A big example of this is Air France 447, where if the pilot had simply let go of the stick the aircraft would have recovered, but typically systems are designed to augment the pilots, not override them.

Departure means that the aircraft has departed from controlled flight. From FAA news:

A Loss of Control (LOC) accident involves an unintended departure of an aircraft from controlled flight

In this video about flight testing F-16s, the test pilot says 'intentionally departed from controlled flight' and later 'the aircraft is prone to departure if mishandled' and 'the aircraft departed in yaw'.

How exactly is "controlled flight" defined? e.g. Not all spins are loss of control, right?

authors: Арсений Кравченко


text:
What are the disadvantages (if any) of using a supercritical airfoil?
The title sums up my question pretty well.
I've searched all over this site, having read many of the questions and answers to various supercritical wing topics, but I haven't found any mention of disadvantages to using them.
Are there any?

My guess: drag or lift/drag ratio at low to medium sub sonic speed is sub optimal.

A supercritical airfoil has these characteristics:

Large leading edge radius
Comparably flat upper surface
Rounded lower surface with a maximum thickness location at around 50%
Flat or even negative camber in the forward section
High positive camber in the rear section (rear loading)

The large leading edge radius allows it to create more lift than comparable airfoils at high angle of attack. After R. Whitcomb re-invented supercritical airfoils (they had first be developed by K. A. Kawalki in Germany in 1940, and British airfoil research resulted in similar shapes, first used in the VC-10), he transferred some of their characteristics to a GA airfoil, the GA(W)-1.
From the Wikipedia article on Whitcomb:

The unusual airfoil unexpectedly aided general aviation as well; its
  rather blunt leading edge allowed it to generate high lift
  coefficients before stalling, and Whitcomb published a low-speed
  airfoil which he called GA(W)-1; it is now routinely used in light
  aircraft and gliders.

As usual, Wikipedia is mostly correct, but the use of the GA(W)-1 on gliders is everything but routine. This gives an indication of their drawbacks:

The low forward camber limits the range of the laminar bucket to lower lift coefficients. A good glider airfoil tries to maintain the laminar bucket almost up to stall.
A positive camber throughout will produce higher maximum lift coefficients than what a supercritical airfoil is capable of. That is why the GA(W)-1 uses only the blunt nose and the rear loading, but not the camber distribution of supercritical airfoils.
The high rear loading gives them a large, negative pitch coefficient which translates into a larger travel of the center of pressure over angle of attack, requiring a larger horizontal tail. In airliners this does not matter because their large flaps dictate the size of the tail.

Funny you (er, Wikipedia) should mention using supercritical wings on gliders... I gleaned (from the Q&A here on Aviation SE) that supercritical airfoils benefit aircraft whose flight regimes are in the high subsonic range.  I can't think of any gliders going that fast!

@pr1268  A few gliders are very fast, even supersonic. For example, the 'Shuttle'...

@pr1268: For one, the GA(W)-1 is not a supercritical airfoil anymore. Also, it is not routinely used on gliders, regardless of what Wikipedia claims.

@xxavier: Okay, but can the Space Shuttle soar on thermals for long periods of time? ;-)

@pr1268  No, but we were talking about gliders, not sailplanes...


text:
What is the Boeing 727 AC Generator Panel Part Number?
Does anyone know the part number for the Boeing 727 AC Generator Drive panel?  I have searched the Internet and have not found the part number.

(Source)

That is an oddly specific question. Not that there's anything wrong with it, just... unusual... Mind if I ask why?

69.17528.5? (source, don't know if it's reliable). I added a photo to your post. Hope you don't mind, you can edit an roll back if that's the case.

The part number is 69-17528-XX, where XX (the dash number) varies based on customer preferences and when the aircraft was produced. Without knowing specifically about the particular airplane the module came from, there is no way to know the part's dash number without physically examining it. See the image below from a search of Icon Aerospace's capability list. Directly searching the capabilities lists of FAA/EASA-licensed repair stations usually yields more reliable results than searching parts "aggregator" or "locator" sites. For example, this list links the part number specifically to a 727.

authors: Мићо Ивановић


text:
Reason behind formation of Mach rings
At night, some jet aircraft like Mirage 2000 leave a trail of discs behind in their jet, these are also known as Mach rings or Mach diamonds.
How are they formed and what atmospheric conditions govern their formation?

authors: Каюм Икромов


text:
May I fly from the right seat due to a temporary disability?
I am a student pilot with, and I have had carpal tunnel for years now. It has progressed to a point where my left hand is frequently weak and/or achy.  I do have use of the hand, and it is quite uncomfortable in the landing flare since I have to control the yoke left-handed when flying in the left seat to leave my right hand free for the lighter-duty tasks of operating the throttle and other equipment.
I am very close to my check-ride and I am scheduled to have surgery on my left hand next month.  I don't want to suspend my training and get rusty.  Also, after the surgery, I suspect that my left hand may not be 100% for some time, and I don't want to miss out on these great flying months.
I have seen articles about pilots with disabilities far greater than a case of carpal tunnel, so I'm wondering if there is a way I can avoid putting my training on hold.
Is it permissible to fly from the right seat so that my weak hand only needs to operate the throttle, flaps, etc. while letting my stronger hand handle the yoke?
Is this simply a request to my instructor/examiner or does this trigger an avalanche of FAA medical paperwork to make it legal?
I realize I would have to adjust to a slightly different sight picture in the right seat but I think that is a relatively minor transition in the grand scheme of things.

Have you seen this question?

There is nothing that makes it illegal, however you may not have access to all the required controls (like the mags/master switches) that an examiner would want, or that you would want in an emergency. Flying right seat may take more training than you realize, and it may be better to just wait it out and take a few more "refresher" hours with the instructor when the hand is better.

By the way, depending on the aircraft and how you are seated, you may not be able to see some critical flight instruments, like the turn coordinator. Especially for new-ish pilots and practicing stalls, glancing at the turn coordinator can mean the difference between stall training and spin training...

Perhaps you could find a tandem aircraft like a Super Cub to train in. Those are flown with your right hand and without any cross-cockpit issues or questions.  Alternatively, take up flying gliders for a while. Great fun, all tandem, and only speedbrakes (no throttle at all).

Just curious, was your hand in that condition when you went for your medical? Seems to me that would be something that requires a special issuance.

Good comments all, thanks. No, the diagnosis came just a few weeks ago but it escalated quickly.

I'd be reluctant to do a checkride with a weak hand. I'd be worried the examiner would send you for a new physical that you won't pass. Then you'd have to go through the special issuance process. They might make an exception for the right seat if you already had a SI but the flight examiner will not be able to say your hand won't effect your ability to fly. Only an AME can do that. If you wait until you are fully healed you could save yourself an awful lot of trouble.

Oh, and best of luck on your surgery and recovery. I know several people with CTS and it really sucks. One of our mechanics at work is out for a second surgery right now. At one point he could barely hold a wrench but his first surgery improved things greatly

§61.53   Prohibition on operations during medical deficiency.

Thanks for the info everyone.  @TomMcW, thanks for the well wishes.  I'm sure everything will turn out fine, just unfortunate that I'll lose out on some valuable time.  But safety trumps all, so I'll just have to be patient.

Generally speaking if your carpal tunnel syndrome is so bad as to preclude normal operation of an aircraft you probably shouldn't be flying from either seat: If something goes wrong you may well need both hands to operate the aircraft (we do have one-armed, and even no-armed pilots, but they generally have medical exceptions, and possibly additional restrictions).
If you cannot complete your training before your surgery your best bet would probably be to defer your checkride until after the surgery - yes this will probably mean additional training time after your surgery to knock off the rust, but you will likely need this anyway (you're going to get rusty during your recovery whether you're a certificated pilot or a student).
Additionally it's probably a good idea to have a safety pilot with you for your first few flights after recovery to ensure you're physically able to perform all the tasks required to safely fly an airplane, and an instructor accustomed to flying from the right seat makes an excellent safety pilot so you could knock off the rust and do your checkride prep at the same time you're making sure you can safely operate an airplane.

Re: FAA paperwork, I'm not an AME but looking at the FAA's Guide for AMEs carpal tunnel syndrome doesn't appear to be disqualifying unless it presents a "medical deficiency" (broadly "interferes with you operating the flight safely").
When you have your surgery you'll be effectively grounded until you recover adequate normal function in your hand to operate the flight controls without risk to the safety of the flight, and more importantly without risk of doing further damage and hindering your recovery.
Having had surgery is something you'll need to report on your next medical application (Question 18, item x: "Other illness, disability, or surgery "). Speak to your AME for details on what you may need to bring to the exam, if anything: Some may want a note from your treating physician stating you've regained normal grip and sensation, others might be OK just checking out your hand during the exam per 67.313 and saying "Your hand seems fine to me."
If you're enrolled in AOPA's Pilot Protection Services you can contact them for information on what you should have available for the exam.

I can see why flying solo or taking a checkride with a weak hand would be a bad idea but is there any reason he should not fly from the right seat with an instructor in the left seat?


text:
How to convert an EASA CPL(H) to FAA CPL Rotorcraft With a Helicopter Class Rating?
I just finished my CPL(H) license and was just wondering if it is difficult to convert your license to an FAA (or TCCA) license.
Do you have to do additional exams or check rides?
It's hard to find a step by step guide to do this, or do you recommend to contact a training organization in the US or Canada to perform the conversion?

I just saw somebody try to do this. They had an EASA CPL(H) and a FAA PPL(H). The DPE needed to have a letter, sent from EASA to the FAA in Omaha, Verified, and then a copy sent to the pilot. This letter is EASA confirming the logbook entries attained in Europe were legitimate. This letter is only valid for six months. Despite getting the necessary flight training from a FAA certified CFI, as per the appropriate requirements, without this letter a DPE can’t administer a practical exam.
You need to pass the FAA practical to get any FAA certificate. Written test requirements vary.


text:
How does ILS (Instrument landing system) work?
How does ILS (Instrument landing system) work?

I know it provides guidance to the runway by  two signals, one modulated at 90 Hz, the other at 150 Hz, but how the airplane lock on those signals?

Which system in the plane is responsible for the ILS? Is the autopilot responsible for it?
If autopilot is used for an ILS approach, at what point does the pilot take manual control?

The ILS works using two components, a localizer and a glideslope.  The frequencies for the localizer are between 108.1-111.95 MHz and the glide slope between 329.15-335.0 MHz.  These frequencies are the carrier waves that the modulation you mention takes place upon.  A pilot is only concerned with the localizer frequency as the navigation equipment knows the paired glideslope frequency for any given localizer frequency.
The equipment for transmitting the signals is pretty well described in your question.  The localizer antenna broadcasts two lobes down the length of the runway for a few miles (typically 18 nm, but some airports like LAX have a much longer serviceable distance).  The glideslope antenna sits around the 1000 ft touchdown zone markers on the runway, offset a little bit from the runway.  It broadcasts a its own two lobes centered around a 3 degree slope (this can vary by installation).  The glideslope is generally usable about 10 nm from the runway, but is generally not used that far out.
The equipment in the plane responsible for using this signal comes in a few parts, an antenna, a radio and a navigation instrument.
The localizer signal is received the antenna used for the normal navigation signals (VOR) and there will be an additional antenna for the glideslope signal.  These signals will first go to a nav radio, which the pilot uses to select the localizer frequency (or a VOR frequency).  If a localizer frequency is selected, the radio will also listen on a specific glideslope frequency.
The data from the radio is then sent to whatever instrument you are displaying the data on.
The most primitive instrument is the VOR head with glideslope-type of needled navigation instrument.

A step up from that is an HSI, which is a bit more intuitive to fly and has better facilities for handling localizer back courses.

On the top end you have electronic primary flight displays that display data on a CRT or LCD screen.

The basis of all of these are following two needles that are shown to the pilot.  One moves side to side and tracks the localizer, and the other moves up and down and tracks the glideslope.  If both of these are centered you are in the middle of both beams and on course.  The position of the needle is determined by which lobe of the transmitter is being received stronger than the other.  When both lobes are received equally the needle will be centered.
To your last question, the pilot has control over the airplane for the entire approach.  The ILS does not take over the airplane.  The autopilot may be slaved to follow either just the localizer, or both the localizer and glideslope, or the pilot may hand fly the approach.  In both cases however, the pilot is in control, not the ILS.
The ILS is usable for at least 10 miles from the antennae.  At many airports you will track the localizer portion of the signal much further out than this.  You will stop using the ILS normally at 200 ft above the ground, although there are special ILS approaches with lower minimum altitudes that require special equipment and training. The majority of ILS approaches however, require the pilot to observe certain visual cues before descending below 200 ft AGL.

Thanks... One more question, you said that 'a navigation instrument' is responsible for using the signal. Is it part of the auto-pilot system?

@GabrielBrito no, not directly. If installed, a flight director will interface with the nav instruments and display a course to fly. An autopilot will follow the flight director. Neither a flight director or autopilot is necessary to fly a normal ILS approach.

@GabrielBrito To clarify something you might be confused about: The ILS isn't there to help the autopilot; its development was wholly unrelated to autopilot technology. It was created to help a pilot land in bad weather; before the ILS was invented, a pilot who tried to land in poor visibility took their life into their hands. ILS was developed as part of the same project that introduced artificial horizons and precision altimeters, and is no more tied to the autopilot than those are (like those, the main purpose is to let a pilot fly without seeing outside).

To add a little more detail on the receiver side and how it's used;
The localiser and glideslope signals are transmitted on different frequencies (the "carrier" frequency) and these are filtered out to leave a mix of 90Hz and 150Hz for each one.  The 90 and 150 are then filtered out separately.
If you have more 90Hz than 150Hz, you are too far left on the localiser or, too high on the glideslope. The guidance indicator is just a display of the ratio between 90Hz and 150Hz.  A 50% ratio means just right!
On your question of "for how long?", a common procedure (it might be different for a particular field or approach) is to fly towards the centre line of the localiser and below the glideslope at an angle of about 30 degrees to intercept the localiser at about 10 miles out.
ATC will vector the aircraft to this point (e.g.  Speedbird 93, descend and maintain 1500 feet, turn left heading 300 degrees.  Cleared ILS approach 27L report established).  The autopilot is usually in approach mode meaning that it will capture the localiser, and in turn the glideslope, and follow the ILS down.
When the localiser is captured, the autopilot will turn the aircraft onto the centre line and the pilot reports established back to ATC.
It is normal procedure to capture the localiser at a height lower than the glideslope at the point of capture so that you capture the glideslope from below.  This is for safety.  If you captured the glideslope from above, then the aircraft may well descend through the glideslope then level out to recapture.  Descending below the glideslope, at what might well be hundreds of feet per minute, is not good.
Finally, most procedures call for a stabilised approach (correctly configured, following the ILS, speed correct, check lists complete, no large deviations in course, height or power settings) by 1000' or go around.  Many pilots, depending on their airlines procedures and conditions, will disconnect the autopilot for the last 1000 feet, sometimes to give practice to the first officer. Some aircraft are cleared all the way down (autoland) but that will also depend on company operations, crew currency and local procedures.
[EDIT]
I deliberately left out the harmonics.  I figured I only had one page ;)

By "harmonics" you mean the side-lobes? They are not harmonics, they are side-effect of use of interference for creating the directional signal. But that would be a question more suitable for [electronics.se][http://electronics.stackexchange.com].

@Jan.  Nope, I mean the harmonics.  The 90 and 150Hz signals, plus the carriers themselves, mix together to form beat frequencies with multiple harmonics.  I was just trying to avoid some smart Alec critiquing my answer as I had not discussed the filtering of harmonics, which would also be better suited to some other site.  Side lobes are something else altogether.


text:
Why does a de Havilland Comet have radiation symbols on the instrument panel?
This image of a De Havilland Comet cockpit shows a radiation hazard symbol on each of the three centre panels, next to the (to me unknown) blue, green, and grey indicators. Why are they there?
I can't find any resources to shed light on it, but then again, I'm no aviator myself so I probably looked in the wrong places.

Source: Wikipedia

That could be a warning that the instrument markings use a radioactive paint that would stay illuminated at night with no cockpit lighting.  The PA23's (mid-1950s vintage) original instrumentation had radioactive instrument markings, if I recall.

Instrument markings back then were painted with luminescent paint containing radium, so they would glow in the dark continuously without having to be energized by a light source.
You can buy luminous watches today with the same feature that use tiny vials containing tritium gas for each marking (much less radioactive than radium and produces negligible amounts of radioactivity, so the watch can't hurt you). These also glow 24/7, but tritium has a shorter half-life and they lose about half their brightness every 7 years or so.
The radium paint was mostly a danger to the women who painted the instrument faces, who would lick the brush tips to get a fine point and could potentially ingest enough radium to develop radiation poisoning.
The radioactivity warning signs may be perhaps a little bit of overkill since the actual radioactivity emissions aren't that high and most of the risk is from ingesting radium directly; it's advised to avoid opening an instrument and poking around without appropriate precautions (If people knew the amount of radiation they're exposed to just being out in the natural environment, they'd probably want to move into a lead house.  I recall a story about a 3 Mile Island Nuclear employee who was setting off the radiation detectors at work while coming IN to work, not while leaving.  From some kind of radiation exposure while off work.) .

There is an interesting article here: https://theaviationist.com/special-reports/radioactive-materials-in-flight-instruments/

Also note that if you open an instrument for repair, you might release radioactive dust which will be bad for your health, if inhaled or ingested. The long half life of radium means that 70 years is not enough to reduce the radiation significantly.

Ra226 is not significantly decayed after 70 years (halfatime around 1600 years IIRC). I have a WWII compass and it is still quite radioactive. However, maybe you are confused by it not being very bright. That is NOT because of the radiactive source, it is because of the luminophor. The alpha particles from Ra226 are strong enough to destroy the luminophor crystals and hence significantly reduce the light output. The largest danger with radium is swallowing it. Alpha radiation does not penetrate the skin but can be very harmful when staying inside the body for a long time. It makes  radon too.

BTW on my compass, some of the luminous markings are not even covered by any glass.

That seems plausible, thank you. On a side note, I've had tritium keychains for decades so I know them very well.

@VladimirF I revised my last para.  Thanks for the comment.

I doubt that the radon story is true. Radon is an inert gas that will be exaled/diluted when you leave an area of high concentration. Also it is difficult to measure radon in low concentrations (in general, measuring alpha radiation requires very short distance between the source and the detector)

@Stefan Only an "aviationist" would rename alpha and beta particles "alpha and bravo particles" as in your link:)

@alephzero I didn't even notice that, and I'm working with radioactivity, not aviation...

@Stefan The only thing that could be set is the personal dosimeter, if worn at home. Which is very unlikely and would only be relevant for some year-long exposure.

Changed it again.  I remember the article from years ago but can't find it.

@JohnK if the worker forgot to take off the dosimeter, it could be radiation from a CT scanner, a baggage x-ray machine, or from cosmic radiation from high altitudes (e.g. flying in an airplane)

@Stefan:  There are radiation detectors in the plants.  Getting in to the area and going between various areas involve passing through detectors.  The Chernobyl disaster was discovered because a worker at a nuclear power plant in Sweden went outside, then came back in through a detector. He was exposed to radiation blowing in from Chernobyl while he was outside, and the detector caught it when he came back in.

@JRE, I know, but that was not the story John K was telling. All this is by the way off topic, so I guess I'll leave it at that.

@JohnK https://www.nytimes.com/1986/08/27/opinion/the-perils-of-radon-and-ignorance.html You were close. Limerick nuclear power plant worker who was exposed to a lot of radon at home.

PUBLIC SERVICE ANNOUNCEMENT: Please do not eat radioactive flight instruments!

authors: Vladimir F Героям слава